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Naming Ketones

(Chemical) Definition of Ketones:

Ketones are organic chemical compounds that include a -carbonyl group (i.e. an oxygen atom attached to a carbon atom by a double covalent bond) such that the carbon atom to which the -carbonyl group is attached is itself attached to two other carbon atoms- as opposed to one other carbon atom and one hydrogen atom, which the case for aldehydes

That is, ketones are a class or category of organic chemical compounds that include a carbon atom attached to both an oxygen atom (by a double covalent bond), and also to two other carbon atoms (by a single covalent bond in each case).

Bearing in mind that carbon atoms form a total of 4 single covalent bonds- or equivalent in combinations of double or triple bonds, a carbon atom attached to both an oxygen atom (by a double covalent bond) and also to two other carbon atoms (by a single covalent bond in each case) cannot be the first- or last - (which are equivalent positions) carbon atom in the chain of carbon atoms that form the organic molecule of which it is a part.
This position of the -carbonyl group (oxygen atom) attached to a carbon atom that is not the last carbon atom in a carbon-chain is important because it distinguishes ketones from a similar category of organic compounds, called aldehydes. In contrast to ketones, aldehydes include a -carbonyl group attached to the end-carbon in a carbon-chain.

Ketone molecules can vary in size up to very long molecules most of which consist of carbon atoms attached to each other and also to hydrogen atoms.

Names of Ketones in General

Ketones are named according to the same system as other organic compounds, with the suffix -one used to designate the presence in the molecule of a carbonyl group (that is, a carbon atom attached to an oxygen atom by via a double covalent bond) such that the carbon atom to which the oxygen atom is attached is not the last carbon atom in a chain or branch, but is always within (the middle of) a chain of carbon atoms. This may be easier to understand by looking at examples of the molecular structures of some simple ketones, as shown below:

As usual in organic chemistry, the first step to work out the name of a ketone molecule is the number of carbon atoms forming the longest straight, i.e. unbranched, chain within the molecule. Having identified the longest unbranched carbon chain within the molecule in terms of the number of carbon atoms in the chain, the main stem of the name of the chemical is as per the system used for naming alkanes.

If the carbon atoms do not form a linear chain but include branches, the longest linear chain of carbon atoms within the molecule determines the base of the name of the compound, onto which is added information about the branches incl. their lengths in terms of the number of carbon atoms in each branch (i.e. methyl- usually indicates a branch consisting of just one carbon atom attached to the main chain, ethyl- indicates a branch of two carbon atoms in length, etc.) and their positions along the longest linear carbon chain (e.g. attached to the 2nd carbon, 3rd carbon, etc.). Branched ketones are therefore more complicated to name than linear ketones.

The simplest linear ketones are named and their structures shown in the tables below.

Names and Structures of simple Linear Ketones
in which the -carbonyl group is attached to the 2nd carbon atom

It is useful to be aware that the same molecule can sometimes be drawn in several ways:

Carbon atoms are counted from the right-side of molecules in the large tables belowbut the structures could have been drawn the other way around, with carbon atoms counted from the left-side, i.e. the following two structures are equivalent and both represent the same structure of 2-butanone:

2-butanone

Likewise, the following two representations are also equivalent ways of drawing the same structure of 2-butanone as those represented above:

Therefore all four of the above representations of 2-butanone are equivalent.

Note: Carbon atoms are counted from the right-side of molecules in the following list but these structures could equally have been drawn the other way around with carbon atoms counted from the left-side, i.e. the following two structures are equivalent and both represent the same structure of 2-butanone:

Likewise, the following two representations are also equivalent ways of drawing the same structure of 2-butanone as those represented above:

Therefore all four of the above representations of 2-butanone are equivalent.

The following table shows the names and structures of the first eight members of the homologous series of linear ketones in which a -carbonyl group is attached to the second carbon atom.

Carbon atoms in chain

Name

and simple formula

Simple Structure

showing bond types but not accurate bond angles

Examples of other names (synonyns)

3

2-propanone (C3H6O)

CH3COCH3

propan-2-one

acetone

dimethyl ketone

methyl ketone

dimethylketal

ketone propane

pyroacetic acid

beta-Ketopropane

dimethylformaldehyde

4

2-butanone (C4H8O)

CH3CH2COCH3

butan-2-one

methyl ethyl keyone

methylethyl ketone

ethyl methyl ketone

methylethylketone

methyl acetone

oxobutane

meetco

5

2-pentanone (C5H10O)

CH3CH2CH2COCH3

pentan-2-one

ethyl acetone

ethylacetone

methyl propyl ketone

methylpropyl ketone

methyl n-propyl ketone

propyl methyl ketone

6

2-hexanone (C6H12O)

CH3CH2CH2CH2COCH3

hexan-2-one

hexanone-2

butyl methyl ketone

n-butyl methyl ketone

propylacetone

methyl butyl ketone

methyl n-butyl ketone

2-hexanone methyl n-butyl ketone

2-oxohexane

7

2-heptanone (C7H14O)

CH3CH2CH2CH2CH2COCH3

heptan-2-one

methyl pentyl ketone

methyl n-pentyl ketone

butylacetone

n-amyl methyl ketone

amyl methyl ketone

methyl n-amyl ketone

n-pentyl methyl ketone

methyl amyl ketone

pentyl methyl ketone

methyl n-pentyl ketone

methyl-n-amylketone

ketone C-7

8

2-octanone (C8H16O)

CH3CH2CH2CH2CH2CH2COCH3

octan-2-one

hexyl methyl ketone

n-hexyl methyl ketone

methyl hexyl ketone

methyl n-hexyl ketone

2-Oxooctane

9

2-nonanone (C9H18O)

CH3CH2CH2CH2CH2CH2CH2COCH3

nonan-2-one

methyl heptyl ketone

methyl n-heptyl ketone

heptyl methyl ketone

beta-nonanone

10

2-decanone (C10H20O)

CH3CH2CH2CH2CH2CH2CH2CH2COCH3

decan-2-one

methyl octyl ketone

methyl n-octyl ketone

octyl methyl ketone

2-Propanone (C3H6O)

Simple Formula:

CH3COCH3

Simple Structure:

*Examples of other / previous names:

propan-2-one

acetone

dimethyl ketone

methyl ketone

dimethylketal

ketone propane

pyroacetic acid

beta-Ketopropane

dimethylformaldehyde

2-Butanone (C4H8O)

Simple Formula:

CH3CH2COCH3

Simple Structure:

*Examples of other / previous names:

butan-2-one

methyl ethyl keyone

methylethyl ketone

ethyl methyl ketone

methylethylketone

methyl acetone

oxobutane

meetco

2-Pentanone (C5H10O)

Simple Formula:

CH3CH2CH2COCH3

Simple Structure:

*Examples of other / previous names:

pentan-2-one

ethyl acetone

ethylacetone

methyl propyl ketone

methylpropyl ketone

methyl n-propyl ketone

propyl methyl ketone

2-Hexanone (C6H12O)

Simple Formula:

CH3CH2CH2CH2COCH3

Simple Structure:

*Examples of other / previous names:

hexan-2-one

hexanone-2

butyl methyl ketone

n-butyl methyl ketone

propylacetone

methyl butyl ketone

methyl n-butyl ketone

2-hexanone methyl n-butyl ketone

2-oxohexane

2-Heptanone (C7H14O)

Simple Formula:

CH3CH2CH2CH2CH2COCH3

Simple Structure:

*Examples of other / previous names:

heptan-2-one

methyl pentyl ketone

methyl n-pentyl ketone

butylacetone

n-amyl methyl ketone

amyl methyl ketone

methyl n-amyl ketone

n-pentyl methyl ketone

methyl amyl ketone

pentyl methyl ketone

methyl n-pentyl ketone

methyl-n-amylketone

ketone C-7

2-Octanone (C8H16O)

Simple Formula:

CH3CH2CH2CH2CH2CH2COCH3

Simple Structure:

*Examples of other / previous names:

octan-2-one

hexyl methyl ketone

n-hexyl methyl ketone

methyl hexyl ketone

methyl n-hexyl ketone

2-Oxooctane

2-Nonanone (C9H18O)

Simple Formula:

CH3CH2CH2CH2CH2CH2CH2COCH3

Simple Structure:

*Examples of other / previous names:

nonan-2-one

methyl heptyl ketone

methyl n-heptyl ketone

heptyl methyl ketone

beta-nonanone

2-Decanone (C10H20O)

Simple Formula:

CH3CH2CH2CH2CH2CH2CH2CH2COCH3

Simple Structure:

*Examples of other / previous names:

decan-2-one

methyl octyl ketone

methyl n-octyl ketone

octyl methyl ketone

Names and Structures of simple Linear Ketones
in which the -carbonyl group is attached to the 3rd carbon atom

The first six members of the homologous series of linear ketones in which a -carbonyl group is attached to the third carbon atom is shown below.

Carbon atoms in chain

Name

and simple formula

Simple Structure

showing bond types but not accurate bond angles

Examples of other names (synonyns)

5

3-pentanone (C5H10O)

CH3CH2COCH2CH3

pentan-3-one

pentanone-3

diethyl ketone

propione

dimethylacetone

methacetone

metacetone

ethyl ketone

diethylcetone

ethyl propionyl

6

3-hexanone (C6H12O)

CH3CH2CH2COCH2CH3

hexan-3-one

ethyl propyl ketone

ethyl n-propyl ketone

3-oxohexane

7

3-heptanone (C7H14O)

CH3CH2CH2CH2COCH2CH3

heptan-3-one

butyl ethyl ketone

n-butyl ethyl ketone

ethyl butyl ketone

ethyl n-butyl ketone

ethylbutylcetone

ethyl-n-butyl ketone

etilbutilchetone

eptan-3-one

8

3-octanone (C8H16O)

CH3CH2CH2CH2CH2COCH2CH3

octan-3-one

n-octanone-3

amyl ethyl ketone

ethyl pentyl ketone

ethyl n-amyl ketone

ethyl n-pentyl ketone

ethyl n-amylketone

3-Oxooctane

9

3-nonanone (C9H18O)

CH3CH2CH2CH2CH2CH2COCH2CH3

ethyl hexyl ketone

n-hexyl ethyl ketone

ethyl n-hexyl ketone

10

3-decanone (C10H20O)

CH3CH2CH2CH2CH2CH2CH2COCH2CH3

ethyl heptyl ketone

3-Pentanone (C5H10O)

Simple Formula:

CH3CH2COCH2CH3

Simple Structure:

*Examples of other / previous names:

pentan-3-one

pentanone-3

diethyl ketone

propione

dimethylacetone

methacetone

metacetone

ethyl ketone

diethylcetone

ethyl propionyl

3-Hexanone (C6H12O)

Simple Formula:

CH3CH2CH2COCH2CH3

Simple Structure:

*Examples of other / previous names:

hexan-3-one

ethyl propyl ketone

ethyl n-propyl ketone

3-oxohexane

3-Heptanone (C7H14O)

Simple Formula:

CH3CH2CH2CH2COCH2CH3

Simple Structure:

*Examples of other / previous names:

heptan-3-one

butyl ethyl ketone

n-butyl ethyl ketone

ethyl butyl ketone

ethyl n-butyl ketone

ethylbutylcetone

ethyl-n-butyl ketone

etilbutilchetone

eptan-3-one

3-Octanone (C8H16O)

Simple Formula:

CH3CH2CH2CH2CH2COCH2CH3

Simple Structure:

*Examples of other / previous names:

octan-3-one

n-octanone-3

amyl ethyl ketone

ethyl pentyl ketone

ethyl n-amyl ketone

ethyl n-pentyl ketone

ethyl n-amylketone

3-Oxooctane

3-Nonanone (C9H18O)

Simple Formula:

CH3CH2CH2CH2CH2CH2COCH2CH3

Simple Structure:

*Examples of other / previous names:

ethyl hexyl ketone

n-hexyl ethyl ketone

ethyl n-hexyl ketone

3-Decanone (C10H20O)

Simple Formula:

CH3CH2CH2CH2CH2CH2CH2COCH2CH3

Simple Structure:

*Examples of other / previous names:

ethyl heptyl ketone

Why stop at ten carbon atoms (in the chain) ? It doesn't. There are more similar linear ketones. We stopped here due to page width.

* The synonyms indicated for compounds listed above are just some examples of alternative names found online and believed to have been used to refer to the substance indicated. They have not all been verified and may include common (non-scientific) names and trade names specific to particular suppliers. The purpose of these lists is to give a general indication of the range of names by which these ketones are, or have been, known.